On Sun, Oct 16, 2022 at 03:06:17PM -0400, Cole Robinson wrote: > On 10/7/22 7:42 AM, Daniel P. Berrangé wrote: > > The libvirt QEMU driver provides all the functionality required for > > launching a guest on AMD SEV(-ES) platforms, with a configuration > > that enables attestation of the launch measurement. The documentation > > for how to actually perform an attestation is severely lacking and > > not suitable for mere mortals to understand. IOW, someone trying to > > implement attestation is in for a world of pain and suffering. > > > > This series doesn't fix the documentation problem, but it does > > provide a reference implementation of a tool for performing > > attestation of SEV(-ES) guests in the context of libvirt / KVM. > > > > There will be other tools and libraries that implement attestation > > logic too, but this tool is likely somewhat unique in its usage of > > libvirt. Now for a attestation to be trustworthy you don't want to > > perform it on the hypervisor host, since the goal is to prove that > > the hypervisor has not acted maliciously. None the less it is still > > beneficial to have libvirt integration to some extent. > > > > When running this tool on a remote (trusted) host, it can connect > > to the libvirt hypervisor and fetch the data provided by the > > virDomainLaunchSecurityInfo API, which is safe to trust as the > > key pieces are cryptographically measured. > > > > Attestation is a complex problem though and it is very easy to > > screw up and feed the wrong information and then waste hours trying > > to figure out what piece was wrong, to cause the hash digest to > > change. For debugging such problems, you can thus tell the tool > > to operate insecurely, by querying libvirt for almost all of the > > configuration information required to determine the expected > > measurement. By comparing these results,to the results obtained > > in offline mode it helps narrow down where the mistake lies. > > > > So I view this tool as being useful in a number of ways: > > > > * Quality assurance engineers needing to test libvirt/QEMU/KVM > > get a simple and reliable tool for automating tests with. > > > > * Users running simple libvirt deployments without any large > > management stack, get a standalone tool for attestation > > they can rely on. > > > > * Developers writing/integrating attestation support into > > management stacks above libvirt, get a reference against > > which they can debug their own tools. > > > > * Users wanting to demonstrate the core SEV/SEV-ES functionality > > get a simple and reliable tool to illustrate the core concepts > > involved. > > > > Since I didn't fancy writing such complex logic in C, this tool is > > a python3 program. As such, we don't want to include it in the > > main libvirt-client RPM, nor any other existing RPM. THus, this > > series puts it in a new libvirt-client-qemu RPM which, through no > > co-inicidence at all, is the same RPM I invented a few days ago to > > hold the virt-qemu-qmp-proxy command. > > > > Note, people will have already seen an earlier version of this > > tool I hacked up some months ago. This code is very significantly > > changed since that earlier version, to make it more maintainable, > > and simpler to use (especially for SEV-ES) but the general theme > > is still the same. > > > > Daniel P. Berrangé (12): > > build-aux: only forbid gethostname in C files > > tools: support validating SEV firmware boot measurements > > tools: load guest config from libvirt > > tools: support validating SEV direct kernel boot measurements > > tools: load direct kernel config from libvirt > > tools: support validating SEV-ES initial vCPU state measurements > > tools: support automatically constructing SEV-ES vCPU state > > tools: load CPU count and CPU SKU from libvirt > > tools: support generating SEV secret injection tables > > docs/kbase: describe attestation for SEV guests > > scripts: add systemtap script for capturing SEV-ES VMSA > > docs/manpages: add checklist of problems for SEV attestation > > > After the fix I mentioned on patch 7, the script worked for my sev, > sev-es, sev-es + kernel setup, with vmsa passed in and vmsa generated. > > Attached is some pylint output, nothing really serious: We've not run pylint on libvirt tree historically, but I wonder if we should introduce it to check all our build scripts too. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
